Sometimes you want to send two stereo signals to one device, for example, when two mixing consoles are to drive a stereo power amplifier. In practice, this is rarely possible without hum loops occurring. The Palmer main solves this problem. It mixes two stereo input signals via a resistor matrix, whereby the input pair A is galvanically isolated via a transformer in order to avoid hum loops. The Palmer main operates purely passively. This makes it particularly low-noise and sound-neutral. Thanks to generously dimensioned transformers, it can also handle high levels of up to +20 dBu without distortion. The transformers also make it possible to assign the input pair A unbalanced; the output signal remains balanced. The passive mode of operation without power supply makes the Palmer main particularly fail-safe, and the aluminium/steel housing and the XLR sockets are also best suited to the rough and tumble of everyday stage use. The Palmer main merge box solves typical sound reinforcement problems in the simplest way with uncompromising sound quality.